[Cutover 1] Freeze v1 and create the protected release/v1 line

[draedful]

Goal

Create the permanent v1 maintenance line from the exact commit that produced the final stable v1 release.

Scope

• Assign the admin and release owners.
• Activate the ruleset targeting release/v1 before creating the branch.
• Announce and enforce the final v1 change freeze on main.
• Complete the final approved 1.x release from main.
• Verify version, changelog, Git tag, GitHub Release, npm artifact, and latest.
• Add the v1 npm dist-tag to the exact final v1 version without changing latest.
• Record the exact final-v1 commit and tag.
• Create release/v1 from that exact commit.
• Verify that the prepared ruleset applies immediately.
• Verify that release-v1.yml permits only 1.x from release/v1 under v1.
• Run the complete v1 release dry-run without publishing an artificial patch.

Acceptance criteria

• The final stable v1 release is verified from npm.
• The exact final v1 version has the v1 npm dist-tag and still owns latest before v2 stable publication.
• The final-v1 commit and tag are recorded.
• The release/v1 ruleset is active before branch creation.
• release/v1 points to the exact final-v1 commit and is protected immediately.
• A non-1.x release attempt fails before publishing.
• A dry-run proves the release/v1/1.x/v1 route.
• main has not yet been promoted to v2.